MBMS is a unidirectional Point-to-Multipoint (P-t-M) multicast/broadcast service in which data is transmitted from a single source entity to a group of users in a specific area. MBMS may comprise a selection of unidirectional point-to-multipoint and bi-directional point-to-point transmissions of multimedia data (e.g. text, audio, picture, video) from a single source entity to a multiplicity of users in a service area. As used herein a Service Area for a given MBMS service is understood to be a geographical area (i.e., set of cells) where the service is made available. The goal of MBMS is therefore to allow the provision of multiple instances of a point-to-point (P-t-P) service with a single transmission over the radio interface as a radio multicast.
Reference with regard to MBMS can be made to a document: 3GPP TS 23.246, V.6.4.0 (2004-09) “Multimedia Broadcast/Multicast Service (MBMS); Architecture and Functional Description” (Release 6), incorporated by reference herein in its entirety. The MBMS has two modes of operation: Broadcast mode and Multicast mode. One significant difference between the two modes is that in Broadcast mode all MBMS users in the service area are targeted, whereas in Multicast mode it is possible to address only a subset of the MBMS users in the service area. Typically, before receiving the service the multicast mode requires the user to subscribe to a multicast group.
The reception of a MBMS multicast service is enabled by certain procedures which are illustrated in FIG. 1, which duplicates FIG. 2 in sub-clause 4.4.1, “Multicast Mode”, of the above-referenced 3GPP TS 23.246, V.6.4.0 (2004-09) document.
An example for the phases of MBMS broadcast service provision is illustrated in FIG. 2, which duplicates FIG. 4 in sub-clause 4.4.3, “Broadcast Mode”, of the above-referenced 3GPP TS 23.246, V.6.4.0 (2004-09) document.
A description is now provided of a conventional release of MBMS resources and a leaving or termination procedure. As is stated in sub-clause 8.1.4.4 of 3GPP TS 44.060, “Radio Link Control/Medium Access Control (RLC/MAC) protocol; Stage 3”, incorporated by reference herein in its entirety, only the network can initiate the release of a MBMS radio bearer. More specifically, it is stated that the “network may initiate the normal or abnormal release of an MBMS radio bearer by transmitting a PACKET TBF RELEASE message to the mobile station(s) on the PACCH” (Packet Associated Control Channel). The TBF is a Temporary Block Flow. In the same sub-clause is stated that the MS shall always stay in broadcast/multicast receive mode when it is receiving any MBMS bearer(s). More specifically, it is stated that: “If the mobile station in broadcast/multicast receive mode is not receiving any other MBMS radio bearers, it shall enter packet idle mode and apply the DRX mode procedures as specified in sub-clause 5.5.1.5, otherwise it shall remain in broadcast/multicast receive mode.”
This requirement must be followed whether the user wishes to receive or to not receive any MBMS service(s). In the case that the user does not wish to receive any MBMS service(s), the MS still receives a MBMS service in the downlink, and may even be required to send feedback in the uplink if commanded by the network.
According to the above-referenced 3GPP TS 23.246, V.6.4.0 (2004-09) document, with a “leaving” procedure a subscriber leaves (i.e., stops being a member of) a multicast group, i.e., the user no longer wishes to receive Multicast mode data of a specific MBMS bearer service. One may consider the leaving procedure to represent a solution, from the perspective of the MS, to stop receiving the MBMS bearer service. However, the conventional leaving procedure is not suitable for MBMS service/sessions(s) that are repeated frequently, since its use results in a considerable amount of signaling in both the radio access and core networks.
According to normal General Packet Radio Service (GPRS) behavior in a mobile-originated release when a downlink TBF has been allocated, the MS simply leaves the channel, such as in a cell re-selection case. However, this type of behavior is not acceptable for use with MBMS since, for example, the MS may be in a feedback mode of operation where the network is expecting to receive an uplink transmission from the MS.
In view of the situation just described several undesirable results can occur, such as unnecessary MS battery consumption, increased signaling load in the network, and a decreased subscriber service satisfaction.